1. Technical Field
The present invention relates generally to the field of semiconductor test and quality assurance methodologies, and more particularly to a method of and system for functionally testing multiple semiconductor devices in parallel in a burn-in environment.
2. Description of the Related Art
An important part of the semiconductor device manufacturing process is testing. Before devices can be shipped to customers, the devices must be tested to determine if the devices perform their intended and advertised functions. Such testing is referred to as functional testing.
Experience is shown that an electronic device will most likely fail in the early part of its operating life if it is prone to failure. The failure rate than levels off throughout the devices normal life and again increases when the device becomes old. Failure during the device's early life is referred to as early life failure, or infant mortality.
Burn-in is an electrical stress test that employs voltage and temperature to accelerate the electrical failure of a device. Burn-in essentially simulates the operating the operating life of the device. Burn-in is usually done at 125° Celsius, with electrical excitation applied to the devices. The burn-in process is facilitated by using burn-in boards upon which devices are loaded. The burn-in boards are then inserted into a burn-in oven, which supplies the necessary voltages to the devices while maintaining the devices at the burn-in temperature. The electrical bias applied may be either static or dynamic, depending upon the failure mechanism being accelerated. Devices are typically maintained at the burn-in temperature from 48 to 168 hours. Devices that survive burn-in should, if they are operated within the rated limits, have low and predictable failure rates.
Currently, burn-in and functional testing are performed separately. Separate burn-in and functional testing increases device manufacture and shipping time.